I'm going to put in my vote for xiao xiao. his were the best and I think i've only seen one other guy make one that was as good. I want to say xiao did like a dozen of them or so and you could tell his skill got better as they went along. transitioning to 3d in some parts in the later ones.

There was a bit of vogue for this sort of stickman fighting animation a few years ago. Xiao Xiao animations were probably some of the first. You might want to look around http://www.stickpage.com/stickfights.shtml to see if the one you remember is there.